Multiple switchboard for telephone-exchanges.



PATENTED NOV. 29- 1904.

` M. G. KELLOGE. MULTIPLE EWITEEEOAEE EOE TELEPHONE EXCHANGES.

APPLICATION FILED NOV. 3D, 1891. RBNEWED 0GT.16, 1899.

N0 MODEL.

i VIII!! l f infiniti.

.lll-ill alllllllnlf llllllurr 'fluvial Witnesses:

Inventor.' /W// 5 ./fe//ogg UNITED STATES Patented November 29, 1904.

PATENT OFFICE.

MlLO Cr. KELLOGG, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SVITCHBOARD AND SUPPLY COMPANY, OF Cl-llCAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

MULTIPLE SWITCHBOARD FOR TELEPHONE-EXCHANGES.

QFECIFICATION forming part of Letters Patent No. 776,06*?, dated November 29, 1904.

Application filed November 30, 1891. Renewed October 16, 1899. Serial No. 733,824. (No model.)

To (all when?, it n1/ty cm1/00771,:

Be it known that l, Mino Cr. KnLLoGG, of Chicago, in the county ot' Cook and State ot' lllinois, (temporarily residing at Geneva, in

the Republic of Switzerland) have invented certain new and useful Improvements in Multiple Switchboards for Telephone-Exchanges, of which the :following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification,

My invention relates especially to a metallic-circuit telephone-exchange system in which each line is permanently grounded at the central ottice througl'i its annunciator; and it consists ot' a system of calling, testing, clearing out, and switching for such an exchange or for such lines, which l shall describe and claim in detail.

ln the accompanying drawings, illustrating my invention, Figure l is a diagram with sections ot' two switchboards to which the saine lines are connected with two lines connected to the same and their central-oliice apparatus. Fig. 2 shows an operators cord apparatus adapted to be used at any board. Fig. 3 shows anoperators test system adapted to be used at any board. Fig. 4 shows a subscribers station apparatus for each line. Fig. 5 shows a polarized annunciator which may be used for each line.

ln Fig. l, A A are sectional Views of sections of two switchboards. Each board has a switch for each line. Each switch has two contact-pieces insulated from each other (except by the circuit connections) and a switchhole adapted to receive a loop switch-plug at its board. The contact-pieces of the switch are so placed and arranged that when a loop switch-plug (shown in Fig. 2 and marked l) D) is inserted into the switch-hole the two contact-pieces of the plug form connection with the two contact-pieces ot' the switch, respectively. In the drawings one of the contactpieces of each switch is a spring and is marked g, and the other contact is placed along the switch-hole and is marked y'. The switch-holes are marked Z L The contact-pieces are mounted on rubber strips of the shape substantially, as shown through thc fronts, of which are the switch-holes Z Z. Other forms oi" switches may be used which have two contact-pieces insulated roin each other and adapted to receive loop switch-plugs and forni connection between their contact-pieces and the contactpieces ot' the plug. fm fw are line-annunciators, and a: :l: retardation-coils, one annnnciator and one retardation-coil for each line. One side or branch of each metallic-circuit line is connected to one of the contact-pieces ol' each switch of the line---say the springs c/ y. The

other side or branch ol the line is connectedV to the other contact-pieces of the switches-A- say j The side or branch ol. the line which is connected to the springs g g is permanently grounded through the annunciator and retardation-coil or' the line. The connections shown in Fig. l are substantially as above described. In Fig. 2., D l) are a pair of loop switchplugs, each plug' adapted to be inserted into each switch at its board and when inserted to form connection between the contact-pieces of the plug and the switch, respectively. The two contact-pieces ot' one plug are connected with the two contact-pieces of the other plug, respectively, by two Aflexible switch-conductors. Z is the operators telephone; B, a calling-generator; fn, a clearing-ontannunciator; Y, a looping-in switch; a calling-key, and B' a test-battery. Each pair of plugs has one switch, one clearing-ont annunciator, and one calling-key. One test-battery and one calling-generator will answer for the exchange.

The connections of the cord system are substantially as shown. ing-in switch the operator can at will bridge or cross-connect her telephone between the pair of ilexible conductors, and by means ot the calling-key she can ground one of the conductors through thc calling-generator. The same conductor is groundedthrough the clearing-out annunciator ol the pair of plugs and the battery B. Only one pair oit plugs, with their special apparatus, is shown. Other pairs may be added to the operators cord apparatus or system, substantially as shown, and in a way which will be apparent to those skilled in the art.

ln the operators test system shown in Fig.

By means of the loop-- IOO 8 T is the test-plug, and t the test-receiving instrument. rl`he plug is connected to a lieXible conductor and is adapted to be brought for testing into connection with one contactpiece-say j-of each switch at its board. It is grounded through its test-receiving instrument. Each operator has a cord system and a test system suitably arranged at her board. In thesubscribers station apparatus shown in Fig. 4, l is the telephone-switch, 2 is the calling-generator, 3 the signal-receiving bell, and 4 the subscribers telephone. The ci rcuits are substantially as shown. The line is on closed circuit at the subscribers station and is grounded through the signal-receiving bell when the telephone is on the switch. Then the telephone is off its switch for use, this ground connection is opened by the contactpoints of the switch. The apparatus should be so connected into the line-circuit that the' calling-generator is in the circuit between the normal ground at the subscribers station when Y the telephone is on the switch and the peri one polarity of currentto line, and thesignalreceiving bells should be such as to respond to that polarity of current. The polarized annu nciators should be so connected into their circuits as not to be operated by the current sent from the calling-generator.

The polarized annunciator shown in Fig'. 5 is substantially a modification of the non` polarized annunciator most generally used for telephone-exchanges and shown and described in detail in the patent of James C. lVarner,

4No. 266,405, and dated October 24, 1882. The

modification consists, essentially, in the employment of a permanent magnet marked N S, attached at one end to the iron plate, which forms the pole-piece of the electromagnet of the annunciator and which therefore charges the cores of the electromagnet with one polarity of magnetism. The permanent magnet is bent so that its other end is in close juxtaposition to the armature of the annunciator and charges thearmature by induction.

The operation of the system is as follows: When a subscriber wishes a connection, he operates his generator with his telephone on its switch. A calling-current passes from ground through one branch of. his line to its ground connection through its annunciator and operates the annunciator. The subscriber then removes his telephone from its switch and by so doing' removes the ground connection from his line and switches hisvtelephone into the line-circuit. rlhe operator on observing the call places one of her switch-plugs in the switch of the line and the switch Y of the pair of plugs being' in position, so that her telephone is in`a bridge across the two flexible conductors of the plugs, she finds out by conversation what line is wanted. She then tests the line wanted, as will hereinafter be indicated, and if she finds it is not switched for use she places the other plug of the pair into its switch. She then presses on the key belonging to the pair of plugs, and a calling-current goes to line and to ground at the subscribers station and rings his bell. The operator moves the switch Y, so that the telephone is disconnected from the circuit` and the lines are connected in a com plete metallic circuit which does not contain any magnet eX- cept the subscribers telephone apparatus. The plugs should preferably be inserted into the switches, so that the contact-pieces of the plugs, which are connected bythe conductor, which is grounded through the clearing-out annunciator, are in coni act with the contactpieces j j' of the switches. One side of the metallic circuit is then grounded through the annunciators and retardation-coils of the lines. and the other side of Athe circuit is grounded through the clearing-out annunciator of the pair of plugs and the battery B'. The battery B should be of such strength infrelation to the clearing-out annunciator and the circuits that when it is connected as described and the subscribers telephones are off their switches for use the annunciator will not be operated; but when the telephones are replaced on their switches and the lines are thereby grounded at the subscribers stations the current from the battery will cause the annunciator to indicate a call. This result is easy to be obtained and depends on the fact that an electromagnet may be so constructed as not to be operated when in circuit with a IOO battery and a certain resistance, but will be operated when the resistance is considerably reduced. By the means above described the clearing-out signal will be sent in by the mere act of the subscribers placing their telephones on their switches. rhe battery may be so related to the annunciator and the circuits that the annunciator will indicate a signal when only one of the telephones is replaced on its switch.

The test system is as follows: WThen a line is switched for use, it is grounded through the battery B', and when a test is applied a circuit is established from the ground through the test-receiving instrument to the line at the point tested and from the line at the point where it is switched to the ground through the battery. rlhe instrument will then respond, indicating that the line is in use. If when the test is made the line is not switched, no complete circuit is established which contains the test-receiving instrument and a battery, and the instrument will not sound. The operator can therefore determine on testing whether or not a line is-switched for use. The resistance with the test-receiving instrument should be such that when the test is made as described and the line is switched IOS , is necessary to accomplish this result.

there will not be enough current to operate the clearing-out annunciator. The test-receiving' instruments may be telephones and as much resistance placed in circuit with them as The switches Y Y may be so left that the telephone normally bridges the various pairs of flexible conductors, and in that case the operator has only to place one of her plugs in the switch of a line to connect her telephone into circuit with the line.

instead of the annunciator fu and retardation-coil for each line an annunciator may be employed which has high resistance and high retardation to telephone-currents.

I claim as my 4invention-w 1. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation, a ground connection to said circuit at the central oiice and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch. having contacts to close the ground connection when the telephone is replaced on its switch and said batteryV having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

Y2. In a telephone-exchange system two metallic-circuit lines switched in metallic circuit for conversation a ground connection to said circuit at the central oflice and a battery "and special clearing-out ann unciator in'said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having' contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on said telephones being' replaced on their switches substantially as set forth.

3. ln a telephone-exchange system, two metallic-circuit lines ea ch normally on closed circuit at the subscribers station and switched in metallic circuit for conversation, a ground connection to said circuit at the central ofhce and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

4. In a telephone-exchange system, two metallic-circuit lines each normally on closed circuit at the subscribers station and switched in metallic circuit for conversation, a ground connection to said circuit at the central oilice and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone a switch and a ground connection at each'subscribefs station, said switch having' contacts to close the ground connection .when the telephone is replaced on its switch in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having' contacts to close the ground connection when the telephone is replaced on its switch and said battery having' such strength as tooperate said annunciator when they are closed to each other on either telephone being' replaced on its switch, substantially as set forth.

6. ln a telephone-exchange system` two metallic-circuitlines switched in metallic circuit 1 for conversation, and the annunciators of said lines through which the circuit is grounded, a ground connection to said circuit at the eentral oflice, and a battery and special clearing'- out annunciator in said ground connection, a switch at each subscribers station, said switch having' contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

7. ln a telephone-exchange system, two metallic-circuit lines switched .in metallic circuit for conversation, and a retardation-coil of one of the lines through which the circuit is grounded, a ground connection to said circuit 'at the central oflice, and a battery and special clearing-out annunciator in said ground connection, a switch at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch, and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being' replaced on its switch, substantially as set forth.

8. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation, and the retardation-coils of said lines through which the circuit is grounded, a ground connection to said circuit at the central oflice and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, aswitch and a ground connection at each subscribers station, said switch having' contacts to close IIO the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch substantially as set forth.

9. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation, a ground connection to one side of said circuit at thecentral oflice, and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

10. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation, a ground connection to one side of said circuit at the central ofiice, and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch, and said battery having such strength as to operate said annunciator when they are closed to each other on said telephones being replaced on their switches, substantially as set forth.

11. In a telephone-exchange system, two metallic-circuit lines each normally on closed circuit at the subscribers station and switched in metallic circuit for conversation; a ground connection to one side of said circuit at the central office, and a battery and special clearing-out annunciator in said ground connection, in combination with atelephone, a switch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

12. In a telephone-exchange system, two metallic-circuit lines each normally on closed circuit at the subscribers station and switched in metallic circuit for conversation, a ground connection to one side of said circuit at the central oiiice and a battery and, special clearing-out annunciator in said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on said telephones being replaced on their switches, substantially as set forth.

13. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation and the annunciator of one of the lines through which one side of the circuit is grounded, a ground connection to the other side of said circuit at the central oice and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

14. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation and the annunciators of said lines through which one side of the circuit is grounded, a ground connection to the other side of said circuit at the central oflice, and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, a switch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

15. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation, and the retardationcoil of one of the lines through which one side of the circuit is grounded, a ground connection to the other side of said circuit at the central ofice and a battery and special clearing-out annunciator in said ground connection, in combination with a telephone, aswitch and a ground connection at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to operate said annunciator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

16. In a telephone-exchange system, two metallic-circuit lines switched in metallic circuit for conversation and the retardation-coils of said lines through which one side of the circuit is grounded, a ground connection to the other side of said circuit at the central oiice and a battery and special clearing-out annunciator in said ground connection, a switch at each subscribers station, said switch having contacts to close the ground connection when the telephone is replaced on its switch and said battery having such strength as to oper- IOO IOS

ate said annuncator when they are closed to each other on either telephone being replaced on its switch, substantially as set forth.

17. In a telephone-exchange system, two metallic-circuit lines connected together into a metallic circuit for conversation, a circuit connection of one of seid lines grounded on one side and permanently connected to the line on the other side, and the annuncietor of said line in Suid circuit connection through which one side of the circuit is grounded, in combination with a clearing-out annuneietor in e ground connection of the other side of the circuit, substantially as slet forth.

18. In a telephone-exchange system, two metallic-circuit lines connected together into a metallic circuit for conversation, e circuit connection of each of said lines grounded on one side and permanently connected to its line on the other side, and the annunciators of seid lines through which one side of' the circuit is grounded, in combination with a clearing-out annuncietor in e ground connection of the other Side of the circuit. Substantially as Set forth.

19. 1n zt telephone-exchange system, two metallic-circuit lines, connected together into a metallic circuit for conversation, a circuit connection of one of said lines grounded on one side end permanently connected to the line on the other side, and u retardation-coil of seid line in circuit connection through which one side of the circuit is grounded, in combinattion with a cleurngout annuncizttor in e ground connection of the other side of the circuit, substantially es set forth.

ln testimony whereof I have hereunto subscribed my neme.

MIL() G. KELLOGG. VVitnesecs:

ANNA P. KuLLoGe, Lunor D. KELLOGG. 

